Dioscorea alata NOT Dioscorea bulbifera turn out to be the edible variety. See Russell Reinhardt comment from forum below.
The tubers often have a bitter taste, which can be removed by boiling. They can then be prepared in the same way as other yams, potatoes, and sweet potatoes.
The air potato is one of the most widely-consumed yam species.It can grow up to 150 feet tall. Air potato can grow extremely quickly, roughly 8 inches per day, and eventually reach over 60 feet long. It typically climbs to the tops of trees and has a tendency to take over native plants.
New plants develop from bulbils that form on the plant, and these bulbils serve as a means of dispersal. The aerial stems of air potato die back in winter, but resprouting occurs from bulbils and underground tubers. The primary means of spread and reproduction are via bulbils. The smallest bulbils make control of air potato difficult due to their ability to sprout at a very small stage.
The vine produces small white flowers, however these are rarely seen when it grows in Florida.
Uncultivated forms, such as those found growing wild in Florida can be poisonous. These varieties contain the steroid, diosgenin, which is a principal material used in the manufacture of a number of synthetic steroidal hormones, such as those used in hormonal contraception. There have been claims that even the wild forms are rendered edible after drying and boiling, leading to confusion over actual toxicity.
In some places, such as Florida where it is considered a noxious weed, it is an invasive species because of its quick-growing, large-leafed vine that spreads tenaciously and shades out any plants growing beneath it. The bulbils on the vines sprout and become new vines, twisting around each other to form a thick mat. If the plant is cut to the ground, the tubers can survive for extended periods and send up new shoots later.
SERIES 20 Episode 22
Aerial Potatoes: These are a type of yam and all yams are tropical vines. They can be grown anywhere in a frost free climate and should produce a good crop. The yam Jerry grows produces its tubers during the summer and has fragrant flowers too.
BLOG - Wednesday, 18 August 2010
Yams are warm climate, winter herbaceous, perennial vines. The swollen, starch-rich tuber is their food store, and this is what most people grow them for - they use them as a potato alternative, baked, boiled, mashed or as chips.
Yams need a frost-free, coastal climate and succeed best where there is summer rain and winter drought. They grow well from Sydney north to FN Queensland and around the Top End into WA. While they’ll grow as far south as Perth, they do better around Carnarvon, and south of the Kimberley expect to give them plenty of water.
I grow winged yam, Dioscorea alata, and aerial potato, D. bulbifera. They’re highly productive. In my Brisbane garden, Winged yam (pictured) can produce a tuber weighing between 15 - 30kg in one growing season. Aerial potato produces tubers in leaf axils on the vine and these are large enough to harvest as well as the tuber in the ground, but they are less productive than winged yam.
To grow them you’ll need compost rich, freely draining soil. I grow my best by planting them in a hole dug two spades deep backfilled with home-made compost. For best returns, water them deeply once a week in dry weather. Give each plant one handful of poultry manure every six weeks during the growing season. I foliar feed mine every fortnight using seaweed.
Yams are vigorous vines, growing to about the spread of a mature passionfruit in one year. In Pacific countries they’re usually planted around the drip line of large trees. Their stems are trained up bamboo canes so they can grow through the canopy unrestricted. Their twining stems readily grow against a fence fitted with wire mesh.
If space is limited, one winged yam can be grown in a space 60cm x 60cm and trained up a sturdy wigwam 3m high. When plants reach the top the cascading growth can be tied in as it descends. They look very attractive trained this way. Just make sure the support is sturdy, as these vines become heavy in summer storms.
Yams are winter deciduous, an adaptation to coping with the winter dry season. In autumn their leaves fall, and during winter their stems gradually break up into pieces. Our cue to harvest yams is when their leaves start dropping.
With aerial yams, the tubers are easily picked off. Save the best for planting.
With winged yam, dig the tubers out carefully. They can grow 50cm or so deep and are easily split in to pieces. After cleaning the soil off them, you’ll notice in the crown that there are tuberlings (see picture, left-hand side). Detach these and replant for next year’s crop. Harvest time is planting time.
Winged yams that are starved of water tend also to produce axillary tuberlings. Well watered ones don’t produce many at all - my five plants only produced four axillary tuberlings. These are worth gathering for distribution.
Yams planted in the cool season won’t need any water until they begin sprouting. In my garden this is around October.
I store my tubers under the house and they stay fresh until growth resumes in spring. When growth resumes the tubers become spongy and less palatable as they draw moisture and nourishment from the tuber.
If you want to harvest yams for cooking, slice off what you need. The cut end dries, seals and heals without going mouldy - as long as they are stored in a cool, dark, dry, well ventilated space, that is.
There are literally hundreds of yam cultivars around the tropical and subtropical regions of the world. The Seed Saver’s Foundation actively encourages local communities to continue growing them. A yam celebration - a community show and tell - which Jude & Michel Fanton encouraged in the Solomon Islands resulted in over one hundred yam cultivars being brought together for the first time. The locals were surprised at their diversity, and now maintain a community conservation collection.
Very few cultivars are grown in Australia. I now have a second winged yam cultivar which I’m eager to trial this year. It was given to me by a keen Brisbane gardener and he reckons it’s purple tubers taste great.
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